Hydraulic cylinder construction



Jan. 10, 1950 F. B. HUNTER HYDRAULIC CYLINDER CONSTRUCTION FANK [iryA/ree,

IN VEN TOR.

Patented Jan. 10, 1950 UNITED STATE-s critici-1 l 12mm 1 :HYDRAULIC'CYLINDER CONSTRUCTION v Frank B. Hunter, Yan Nuys, Vassigner .to

vaginali-Misra L i :original application august zo, i945.. serial Nor.

611,623, 110W N0. 2,451,089, dated Octor.

-her l2, 1948. Divided and ithisapplicaton Sep. -tember .13, .1948,Serial No. 48,988 y when Ya great deal of care 'is necessary in order tohold close tolerances in a long bore, `the operation becomescorrespondingly expensive. If the price of devices of this kind,particularly when made in large sizes, is to beheld within an economicalrange, the cost of producing cylinders with a long bore need be held toa reasonable minimum. n

Generally stated this invention not only relates to a 4.power cylindercombination whereby vease of manufacture .is attained but -also relatestoa construction whereby the power piston 'operating in a pressure iiuldcylinder may be held .at one end of its stroke in an automatic .mannerand .then released by the pressure fluid when the pressure iiu'd reachesa desired operating ,pres-v sure, thereby allowing the power piston tomost eiectively perform the functions for which it is intended. Thelatter phase is the subject matter of this application, which is adivision of Serial No. 611,623, iiledAugust 20, 1945,'n0w Patent No.2,451,089.

It is therefore among the objects of my invention to provide a.hydraulic cylinder construction which will permit the assembly of ahydraulic cylinder of precise dimensions from parts where a relativelygreater latitude is permitted in holding the critical dimensions.

Another object of my invention is to .provide a iiuid pressure cylinderincluding )a head provided with pressure .iiuid -actuated andspringbiased means for holding a piston in position adjacent such head,against accidental displacement, until such time as adequate pressurefluid is available to release and operate the piston during a workingstroke.

Still another object of .my invention is to provide a hydraulic cylinderof. relatively long stroke in proportion to its diameter which isadapted to operate eiiiciently upon a sudden demand so that hydraulicliquid under relatively high pressure, when released by operation of asuitable trip, will be utilized at high efciency vin order to operatethe' cylinder throughout the full length oits stroke. y'

With these and other objects in View; mjy 1inventionf-co'nsists in ltheconstruction, arrange; ment and combination of thel yvarious parts of mydevice whereby the objects contemplated are attained, as" Ahereinafter'more' fully set forth, pointed out'in .myclaima and Aillustrated in theaccompanying drawing, in Which.

Fig. 1 is a 'longitudinal sectional YView 'of "the hydraulic cylinderassembly showing Athe piston in 'initial'position Fig. 2 is acrosssectiontaken on the oiFig. 1' through a connection. "Figf3 is a sectiontakenl on 'the lineII-III of Fig. 1 showingdetails of a trip operablewith Jthe device. Fig'. 4 is a longitudinal sectional view lied form Vofmy device.

'.machining'out' the bores of cylinders 'oi' anyv kind, the operationcustomarily'consists of an initial rough bore `followed. by one or moreiinishedbores so 'that the inside wall may be perline Iii-#II of iamodiiectly smooth and in a true cylindrical shape.

Practical diiliculties invariably arise, making it impossiblefto make aperfectly cylindrical shape. For variousv uses dilierentl tolerances may"be permitted. In 'hydraulic cylinders Wide tolerances may sometimes bepermissible if the hydraulic ypressure is not'high. In other instanceswhere the hydraulic pressurev lis relatively'high or Where it isundesirable to have Aeven a 'slight leak past the piston within 'the'cylinder', much vcloser tolerances are desirable and even necessary. Tohold close tolerances when the 'bore is relatively long necessitates theuseof Vexpensive machinery and expensive 'machine setups. .It 'willYalso'f'be'"appreciated that 'almost any machiningoperationsareexpensive as .compared With casting operations. In View,however, of the relatively cheapness of casting operations, Wheretheycanbe utilized 'to Vgood advantage, they .permit asuiiicient savingof machining operations so that a device utilizing some castingoperationshas .a .great advantage overVv a .corre spending device which'is vmade entirely by those machining operations. u" *"Inthe'embodirnent chosen to illustrate my in-y vention there is shownajhydraulic cylinder assembly which consists .of 'a full length 'tubularliner Il), `the'inside Wall 'l1 of Whichforms the bore of a hydrauliccylinder. The tubular liner maybe of suitable commercial 'tubing drawn"to dimensions Lwithin permitted V'tolerances andcut may be cast, sincethe dimensions need not be.

held toa close tolerance so long as the liner is adapted to be readilyinserted into 'the casing.

The casing I2 is provided with an end I4 having an axial aperture I5 inwhich'is positioned Aa packing sleeve I6 retained in place by a packing`IlIS nut I1. Ring seals vI8 andIS are provided in order to make afluid-tightt.

The casing I3 is provided withan end portion or head 2D of specialconstruction in order to the chamber the iluid is .adapted to flowthrough a passage 41`into the interior of the hydraulic cylinder whereits force can be exerted upon a 'face 44 of the piston 22.

Inlet port 45 is shown entering chamber 46 at right angles thereto.Chamber 46 may be the central portion ofa longer chamber 48extendaccommodate a hydraulic release indicated generally by thereference character 2 I.

Within the liner is positioneda piston 22 which has a sliding fit withinthe 4innerwall IIV` ofthe liner and which is provided with a ringpacking 23 which has a sliding friction ilt against the wall of theliner. A piston rod 24, here shown tubular in section, isanchored atone'end 25 to thel piston and extends outwardly past the packing gland I6and packing. nut I1 within which it has a sliding t.` At the outer vendoi the piston rod is provided respectively with ilanges 30 and3I whichare Vshown abutting against eachother Vand which have their respectiveinner corners 32 and 33 beveled so as to provide a recess therebetweenwithin which may be inserted a packing ring 34.

For holding the flanges in abutted relation there is provided a pair' ofsplit rings 35 having lateral nanges 36 overlying the sides of the'angeson the ends ofthe casings. .When a ring such as 35 is used, itis usuallysplit along a plane passing along the axis (diametrically) so as to formtwo halves, thereby giving rise toa pair of semi-circular split ringportions.

. On the outer surfaces of the split rings is provided a. rim portion31. For holding the split rings in position there is provided acontinuous ringl 38 which surrounds the split rings in assembledposition and which bearsatone edge lagainst the rim 31. So Vthat thecontinuous ring will remain in place, the split rings are provided witha recessed portion 39 into which may be positioned a snap ring V40.`

When the split ring assembly is applied to the nanges of the casing inorder to hold them together, the packing ring 34 is compressed betweenthe inside beveled faces of the flanges and theadjacent outside wall ofthe liner V'soas to bev uid-ti'ght and prevent any hydraulic pressurewithin the interior of the liner from escaping at this connection. Aconstruction 'of this Vkind makes it unnecessary to have a snug fitbetween the outside wall ofthe liner and the rinterior of the casing.v YY f lA similar construction srshown in the modified form vin Fig. 4wherein the ring .assembly is anchored in place upon the piston. Amplespace ing transversely of the axis of the attached cylin- -'der,whilepassage 41 is axial with respect to the cylinder. f

vThe piston, however, is normally locked in the initial position Vshownin Fig. 1 so that although pressure exerted by the hydraulic fluid maybe present upon the piston, there will be no movementof the pistonuntilthe pressure exceeds a certain predetermined figure.

Held in 'thehead 29 and extending from 'either end thereofjis a sleeve49, said sleeve being provided with a port' in alignment with port 45and another port in alignment with the transverse passageway 41.Thissleeve is provided with a cap 5i) ateach end to thereby fornichamber 48. A pair of opposing release pistons 5 I isfslidablypositioned within the` sleeve 491, Vthese pistons being spring pressedin the direction of the central chamber by means of coiled springs 53.Suitable packing rings 52 are carried by each of the release pistons andexternal packing rings 54 completely seal the sleeve in position.

In order to prevent" the release pistons 5I from rotating and in orderto keep the ports of the sleeve 49 in alignment with the passageways 45and y41, each of the pistons is provided with a longitudinal'- s101355adapted to slidably receive dogends 56v of set screws 51. These dogscrews also .prevent the release pistons from coming into completecontact. 'Y

The end of eachV release piston is specially shaped in thatit isprovided with a semicircular flange 58'which is designed to engage witha portion Vof anv annular recess 58' locatedV beneath a conicalih'ead5601 a1 pin 60, said head being slightly smaller than .pin 6 6. It willbe noted that the'pin hasV a flange 6I resting against the face'44 ofthe piston. The pin extends through the piston and'into a threadedengagement 62 with the piston rod 24. The pin is thus securelyisprovided around the outside end -of the pin so that hydraulic iluidmay pass freely along its sides through passage 41 and intojthehydraulic cylinder wherein it presses against the face 44 ofthe'piston.At the other end I4 of the cylinder there is provided a second port 63.

In operation, the piston, in initial position, is located at the end 'ofthe cylinder member las shown in Fig. v1 wherein the pin is locked byreason of the fact that the springs A53 press the release pistonsinwardly 'so `that the ends engage :beneath the head 59 of lthe pin.Fluid under pressure is then admitted into they port 45 from which it isenabled to pass through the bore 4i into thev cylinder where it sets upa pressure against the piston. As the pressure builds up the piston willnot move but will remain fixed in position so long as the releasepistons engage the pin."After uid pressure has built up to an amountsuicient to overcome the pressure of the 'springs 53, the releasepistonswill be pushed out- Wardly out of engagement with the head of the pin.When this is accomplished, the pin will be released and the piston22'will be moved from the position shown in Fig. 1 to a positionadjacent the other end of the cylinder member. Meanwhile, should thereby any fluid within the cylinder on the opposite side of the piston, itmay be exhausted outwardly through the port 63.

By the means described, it is not possible for piston 22 to creep orpartly move; the piston will only move when adequate pressure fluid isavailable to complete the working stroke. This is an important featuresince it insures that an adequate amount of power is available beforeinitiating the power stroke.

To return the piston to its initial position it is necessary only toreverse the ilow ofthe pressure fluid so that it enters the port 63,driving the piston from the right hand end of the cylinder as viewed inFig. 1 to the lefthand end. As the piston is pushed against the lefthandend, the head 59 of the pin penetrates into the space left remainingbetween opposite ends of the release pistons forcing them far enoughapart so that the head of the pin may be completely inserted in orderfor the annular recess adjacent the head to be re-engaged by theappropriateportions of the release pistons. It will be noted from thisthat the cylinder may be set to operate at a high, siddenly released,instantaneous pressure, even though the piston stroke is long.

It will be noted from the description given that the cylinder (orcylinder portions) are free from threads cut thereto. In the modicationshown in Fig. 1 the end pieces are an integral part of the cylinder. Inthe modication shown in Fig. 4, the end pieces are simply buteffectively connected to the cylinder. Here two split rings 35 are used.By eliminating threaded ends, the problems ordinarily encountered incutting threads precisely so that an engaging cap will be in properalignment with the axis of the cylinder are eliminated. The boring ofthe cylinder and the cutting off of the ends of such cylinder may beaccomplished upon the same machine tool and result in end faces whichare perpendicular to the axis of the cylinder. Any slight misalignmentof the cylinder sections I2 and I3 is nullied by the continuous innerliner.

It will also be evident that cylinders constructed in accordance withthis invention may be dismantled while one end of the cylinder is stillattached to the structure which carries the cylinder. It is onlynecessary to remove the snap ring 40 and slip the retaining ring 38 oithe split ring sections 35 in order to remove one of the cylinderportions I2 or I 3.

In actual practice it has been found that the construction shown is oflighter Weight than that available heretofore. Although specic referencehas been made to hydraulic cylinders, it will be obvious that theconstruction here shown may be used not only with hydraulic liquids butalso with pneumatic fluids.

I claim:

1. In a hydraulic cylinder assembly comprising a cylinder memberproviding a smooth-surfaced bore, a piston slidable therein, a valvedevice for controlling the flow of hydraulic fluid to the cylindermember comprising an axial bore at one end of the cylinder, a transversebore intersecting the axial bore forming a chamber at the intersection,a locking pin on the piston adapted to extend into the intersectionhaving an annular recess adjacent the end thereof, a spring pressedrelease piston having a sealed sliding fit in the transverse bore oneach side thereof and having an inner end of each shaped to engage apart of the annular recess on the pin in initial position, and an inletfor hydraulic fluid in communication with the inside faces of said lastpistons whereby said last pistons are moved to a second positionreleased from engagement with the pin when the pressure exceeds apredetermined amount.

2. In a hydraulic cylinder assembly comprising a cylinder memberproviding a smooth-surfaced bore, a piston slidable therein and a Workrod attached to the piston extending from the cylinder member, a valvedevice for controlling the ow of hydraulic fluid to the cylinder membercomprising an axial bore at the end of the cylinder member remote fromthe Work rod, a transverse bore intersecting the axial bore forming achamber at the intersection, a locking pin on the piston adapted toextend into the intersection having an annular recess adjacent the endthereof, capped sleeves adapted to close each side of the transversebore, a spring pressed release piston having a sealed sliding t in eachsleeve and having an inner end shaped to engage a part of the annularrecess on the pin in initial position, guides for maintaining movementof the release pistons in a xed direction and an inlet for hydraulicfluid in communication with the inside faces of said last pistonswhereby said last pistons are moved to a second position released fromengagement with the pin when the pressure exceeds a predeterminedamount.

FRANK B. HUNTER..

REFERENCES CITED The following references are of record in the ille ofthis patent:

UNITED STATES PATENTS Number Name Date 2,074,772 Brown Mar. 23, 19372,258,376 Clothier et al Oct. 7, 1941 2,342,812 Martinson Feb. 29, 19442,349,244 Brown May 23, 1944

